Backend: introduce Android version check

- checks the supported.versions prop in anykernel.sh and matches against it to prevent users flashing incorrect kernels for ROM versions
- supported.versions can be a list, e.g. "7.1.2, 8.0, 8.1" or a range, e.g. "8.1 - 9" of versions in the correct formatting for that Android version in ro.build.version.release in /system/build.prop

tools/ak2-core.sh

@@ -1,4 +1,6 @@
 ## AnyKernel methods (DO NOT CHANGE)
+# osm0sis @ xda-developers
+
 # set up extracted files and directories
 ramdisk=/tmp/anykernel/ramdisk;
 bin=/tmp/anykernel/tools;